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A/C Sizing Calculator
It's very important that you select the right sized unit for your home. An undersized unit will not have the ability to effectively handle the heat in your room, causing the unit to overwork and not perform optimally. On the other hand, an oversized unit can cool a room quickly, but can create a "cold and clammy" feel due to the humidity levels that aren't lowered properly. We have provided a quick and easy guide to estimating a proper-sized air conditioner to fit your needs.
1. Compute the Area of the Room: Assumes an 8-foot ceiling.
(Enter the dimensions of the room you're trying to cool)
2. Select your Air Conditioning Needs:
In what environment will you be using your air conditioner?
- Low Heat or Night Time Only - windows/exterior walls mostly shaded from direct sunlight, well-insulated construction. Good figure for bedrooms or apartments in well-constructed high-rise buildings.
- Normal Conditions - windows/exterior walls moderately (50-70%) exposed to direct sunlight, ceiling with attic space above.
- High Heat or Direct Sunlight - large window and wall area exposed to direct sunlight, heavy afternoon sun, and open beam ceilings.
(Select the most appropriate choice from the following)
3. Compute the Monthly Usage in Hours:
4. Select Your Service Area for Price of Electricity*:
5. Determine Monthly Energy Cost by EER:
The Energy Efficiency Ratio, or EER rating, tells you how efficient the appliance is in energy consumption. The higher the number rating, the more energy-efficient it is. Based on the A/C size estimated above, here is an example of how much it would cost to run the unit if it had an 8, 10, or 11 EER rating:
* Default cost per kWh for customers on Oahu, Maui, Molokai, Lanai and Hawaii Island is based on the average 2022 residential rates.
** Enter a custom EER value to illustrate costs of Air Conditioners with other EER ratings.
Sizing of a room air conditioner depends on many factors, such as area of room, ceiling height, number of occupants, insulation and type of construction. We recommend you consult with the sales person at the showroom you visit to be sure that the size selected will meet your individual requirements.